On October28th and 29th, 2016, accepting the invitation of President of Hanoi National University of Education, Prof.Dr Takaaki Kajita, who received the Nobel Prize in Physics in 2015, had a symposium in Hanoi National University of Education.

Professor currently is the director of the Institute for Cosmic Ray Research. The cooperation and development in scientific research project for Vietnamese officials and students, especially in the field of gravitational waves and cosmic ray studies is the focus of the first meeting between him and the Board of Trustees.

On October 29th 2016, Prof.Dr. Takaaki Kajita gave a public lecture on the 2015 Nobel Prize in Physics entitled "Neutrino fluctuations." It was attended by a large number of staffs, lecturers, students in HNUE, those from other universities in Hanoi, and even scientists at Institute of Physics, Vietnam Academy of Science and Technology, Vietnam Physical Society, Institute Vietnam Atomic also attended.

Prof.Dr. Takaaki Kajita gave a lecture about the more-than-30-years process of continuous research on the neutrino particle, which led to the Nobel Prize in Physics in 2015.

The existence of the neutrino particle was first recognized in 1930 but it was not until 1956 that two American physicists found traces of the particle. However, the neutrino particle is still a mystery. The neutrino particle is a non-charged particle, long thought to have no rest mass. However, he has proven otherwise.

In 1998, Kajita's team discovered the neutrinos in cosmic rays that hit the Earth's atmosphere. In 2001, McDonald's team also discovered neutrinos created from the sun. Using a highly sensitive detector set up below 1000m, scientists have discovered that neutrinos can change their properties through space - a phenomenon known as neutrino oscillation. This result is evidence that the neutrino particle has mass.

Neutrinos are one of the most abundant particles in the universe. The trillions of neutrinos flickered through us every second. Neutrinos are particles that are almost massless and have no charge so it rarely interacts with anything else. This makes it difficult to study it.

Now, scientists have demonstrated that neutrinos have mass. Given the abundant number, it is estimated that the total weight of the neutrino particles in the universe is the same as that of all human stars observed.

This discovery gives an insight into the innermost activity of matter and alters our view toward the cosmology. The discovery of the two scientists digs deep into the mysterious world of neutrino particles, and helps solve some related problems.

Prof.Dr. Takaaki Kajita has inspired a number of audiences. They asked a lot of questions which ranged from advanced modern science, issues of mass science, cosmology, to share experiences, passion for scientific research. Professor also highly appreciated the scientific enthusiasm of young people in Vietnam.